Migration Stimulating Factor (MSF) is a stress-response molecule expressed by epithelial and stromal cells in fetal skin and common human tumours. MSF is not normally present in healthy adult skin, but is transiently re-expressed during wound healing. Human recombinant MSF displays a number of potent bioactivities relevant to wound healing and cancer progression, including the stimulation of cell migration (target: carcinoma cells, keratinocytes, dermal fibroblasts, endothelial cells), stimulation of hyaluronan synthesis by fibroblasts, and angiogenesis in vivo and in vitro (S. L. Schor, I. R. Ellis, S. J. Jones, R. Baillie, K. Seneviratne, J. Clausen, K. Montegi, B. Vojtesek, K. Kankova, E. Furrie, M. J. Sales, A. M. Schor, R. A. Kay. Cancer Res. 2003, 63, 8827; and S. L. Schor, A. M. Schor, R. P. Keatch, J. J. F. Belch. The Wound Healing Manual McGraw Hill, New York, 2005, pp. 109-121).
MSF is a truncated isoform of fibronectin produced from the primary fibronectin gene transcript by a bypass of normal alternative splicing involving read-through of the intron separating exons III-1a and -1b. Intron retention results in the inclusion of a unique 30 bp coding sequence. MSF protein is consequently identical to the 70 kDa N-terminus of fibronectin, including nine type I and two type II modules, and terminates with the sequence coded by module III-1a and a unique decamer not present in any previously described “full-length” fibronectin isoform.
The IGD (isoleucine, glycine, aspartate) tripeptide motif, a highly conserved feature of the fibronectin type I module, is present within the third, fifth, seventh and ninth constituent type I modules of MSF (FIG. 1) (R. Hynes, ‘Fibronectins’, Springer-Verlag, New York, 1990). Interestingly, synthetic trimer and tetramer peptides containing the IGD motif exhibit the same range of biological activities as those displayed by MSF (S. L. Schor, I. Ellis, J. Banyard, and A. M. Schor, Journal of Cell Science, 1999, 112, 3879). Furthermore, in vitro mutagenesis and analysis of IGD-recombinant constructs has demonstrated that the motogenic activity of MSF on target fibroblasts is mediated by the IGD sequences.
Studies have implicated the related RGDamino acid motif (located in the tenth type III repeat module) in mediating the cell migrating stimulating effects of both native fibronectin and its cell-binding domain. Significantly, small RGD-containing synthetic peptides did not stimulate cell migration; indeed, these peptides inhibited the adhesive and migration stimulatory activity of larger protein domains containing the RGD motif by competition for receptor ligation.
International patent application published under number WO 99/02674, relates to peptides containing the IGD motif and their use as cell migration modulators.
There is a need to provide molecules which express MSF/IGD bioactivities and show improved stability compared to the IGD tripeptide. Such molecules may be useful as therapeutic agents for the management of patients with impaired wound healing and other pathologies requiring the stimulation of cell migration and angiogenesis.
It is an object of the present invention to provide IGD mimetic molecules having MSF and/or IGD bioactivity, such as stimulatory and/or inhibitory activity.